This invention relates to sodium sulphur batteries comprising a plurality of modules, each module containing one or more sodium sulphur cells. The invention also relates to such modules.
A sodium sulphur cell operates at a temperature at which the anodic reactant (sodium) and the cathodic reactant (sulphur/sodium polysulphides) are both liquid. Typically the operating temperature is 350.degree. C. Provision therefore has to be made to heat the cells to bring them up to the operating temperature. A sodium sulphur cell however is capable of a high current output and, in normal operation, the heat generated internally in the cells by the current therethrough is more than sufficient to maintain the required temperature. In general the cells in a battery are thermally insulated so that the cells remain at the operating temperature during intervals when current is not being drawn.
When a large number of cells are assembled close together to form a battery, then there is a possibility of overheating occurring during normal operation and provision has to be made for cooling the cells.